Many electronic systems for usage in various applications such as network communications, telecommunications, data transmission, and many others are susceptible to damage resulting from transient energy. Lightning and other surge energy events can create rapid electrical energy transients. Such transient events can damage electronic circuits or equipment.
Some circuit arrangements include two or more circuits that are connected but operate with reference to ground potentials that may be different. In response to various conditions, electrical current may flow between different ground domains so that the ground potentials can bounce relative to one another, which may be a source of common-mode noise. In a communication application, the generated noise can interfere with communication between ground domains.
A conventional clamping circuit can be used to prevent another circuit from exceeding a predetermined voltage level and functions by sensing the output voltage of the monitored circuit and, if the output voltage approaches or exceeds the limit, applying a load. The applied load draws current in a regulated manner to prevent the output voltage from exceeding the limit. The clamp circuit generally operates with lower output impedance than the monitored circuit so that the circuit is overpowered.